This invention relates to method and apparatus allowing visual access to the interior of a tire wheel assembly under dynamic conditions. More particularly, the present invention relates to a wheel rim having at least one window such that the interior of a tire mounted on the wheel rim may be viewed under dynamic conditions such as those provided by a dynamometer test machine.
Vibration felt by a vehicle driver through the vehicle seat, steering wheel, and acceleration pedal are typically directly related to force variations encountered at the tire footprint which may be caused by a variety of sources. These sources include, but are not limited to, imbalance of the tire wheel assembly, runout of the wheel and/or tire, irregularities in the structure of the tire (non-uniformity), brake drag, wheel misalignment, road disturbances, worn linkages, etc. In recent years, automobile vehicles weights have been generally declining in order to improve gas mileage. A result of the weight loss is that the suspensions and wheel support parts have become lighter and more susceptible to vibration. Vibration, especially vibration due to non-uniformity of the tire and imbalance due to tire and/or wheel runout, is now a prominent issue for tire manufactures who are also under economic pressure to do more with less. In addition, lead balance weights used to correct tire wheel assembly imbalance, long considered a health concern, will likely be banned and a replacement for lead will need to be used to manufacture the weights.
It has long been known that inserting various materials into the interior of a tire wheel assembly could provide a benefit of balancing the tire wheel assembly. Internal flowable materials have long been used as a staple for many fleet managers in the trucking industry to help combat vibration, promote even tire wear, and extend tire life. The cause behind this benefit has been described in a variety of manners, the most common being the principle of mass balancing. Based on this theory, during tire rotation, free flowing materials contained the tire wheel assembly will seek a distribution in balance about the center of rotation and will tend to offset any imbalance inherent in the tire wheel assembly. However, while the performance of the internal materials could be verified both subjectively and by objectively by testing, none of the theories on the way the internal materials worked could be substantiated because it was impossible to see into the interior of the tire wheel assembly to see how the materials acted under operating conditions. Furthermore, without proving the mechanics of how the internal flowable material works, it has been recognized that at least some internally flowable materials not only work to reduce the vibratory effects of imbalance, but also work to reduce force variations due to non-uniformity of the tire as well as dampening other sources of vibration and noise.
Accordingly, internal flowable materials are positioned to help the tire and vehicle manufactures provide a better ride for their customers. However, testing variations of different materials may be necessary to optimize the make-up and/or amount of internal flowable material for a particular tire/vehicle application. This testing could be facilitated by a definite knowledge and comparison of how the internal flowable materials react to forces within the tire under dynamic conditions.
Other problems with the state of the prior art is with unsubstantiated and competing claims by some internal flowable material manufacturers which may confuse potential consumers as to how a product actually performs within a tire. With the introduction of various competing internally flowable materials, additional theories have been forwarded by these manufacturer in order to substantiate claims of superior performance of a particular material. As an example, one such manufacture using a material comprising glass beads has claimed that their glass beads, once properly positioned by the rotation of the tire wheel assembly to a position causing balance of the tire wheel assembly, will remain in this balancing position along the innerliner of the tire due to electrostatic cling produced by the tribological forces generated by the glass beads rubbing against the innerliner of the tire and against each other. The manufacturer has claimed that the glass beads remaining in position provided a benefit in that the internal balancing compound did not become displaced when the vehicle stopped, thus the tire wheel assembly remained in a dynamically balanced condition. As with the theories as to how these internal flowable materials worked, the electrostatic cling theory could not be substantiated or disproved because it was impossible to see into the interior of the tire wheel assembly to see how the materials acted under operating conditions.
There are a multitude of additional problems related to the inability to view the interior of a tire wheel assembly. Improved performance tests could be developed such as monitoring the development of innerliner cracking or monitoring specific interior areas of the tires under specialized test conditions.
Therefore, there remains a need in the art for a wheel and method that will enable the interior of the tire wheel assembly to be viewed under operating conditions.
An object of the present invention is to allow the interior of a tire to be viewed when the tire is mounted on a wheel rim as part of a tire wheel assembly. These and other advantages are provided by a wheel rim having at least one aperture formed therein. A transparent material is attached to the tubewell in a position covering the aperture in a manner preventing air loss and forming a window through the wheel rim.
These and other advantages are also provided by a tire wheel assembly comprising a tire mounted on a wheel rim having at least one aperture formed in a tubewell portion of the rim and a transparent material attached to the wheel rim and positioned over the aperture forming a window through which an interior surface of the tire is visible.
These and other advantages are also provided by a method of viewing the interior of a tire of a tire wheel assembly undergoing dynamic operations comprising the steps of providing at least one window in a tubewell portion of a tire wheel assembly; causing the tire wheel assembly to rotate against a test surface; and directing a camera toward a predetermined position where the window will occupy during at least a portion of its rotational path.
With the above, and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description and the several views illustrated in the accompanying drawings.